Ventilating block and brick, non cavity wall and high soil problem

[DeanAlan]

Hi All,

 

We have an extension being planned, in final stages of building control plans, with a block and beam floor that needs ventilating.

 

Telescopic vents I hear you say ?

 

Well, the foundation masonry - up to the SIPs being used for the structure, has no cavity (driven by SIPs only being 175mm wide).

 

The block and beam is at about the same level as the external ground and so we are having a challenge on how to ventilate it correctly as no cavity to put the telecopic vents in and not enough clearance from ground to put a straight through vent.

 

I have considered a telescopic vent where the telescope is outside the building - and possibly bricked around to give it some longevity.

Have considered taking the ground level down and maybe holding it back with something, masonry maybe some type of grille.

 

Any advice / product suggestions?

 

cheers,

-Dean

 

[Mr Punter]

Use a telescopic vent with the air brick being just under the plinth brick.  The vertical bit is only about 50mm wide so you can just cut the floor block to suit.  Obviously you need to place between the beams.  It does very slightly reduce the bearing for Marmox but it looks like the soleplate spans onto the edge of the plinth brick anyway.

 

Make sure your ground level is 150mm below the sole plate / DPC.

Edited October 20, 2021 by Mr Punter

[Russell griffiths]

Just what mr punter said. 

I think your looking at the drawing and thinking the vent is the length of the wall, whereas it’s just a 225 section, position between beam ends. 

[DeanAlan]

If I understand correctly then cut the floor block that is in positioned on the beam to provide the riser part of the telecope (like you say, only 50mm) to just below the Marmox to then align with airbrick below the plinth brick. I think my architect was concerned about the Marmox bearing but as you say, only taking away 50mm of 140mm and not for the whole span of the Marmox either.

 

What are telescopic vents actually solving in this case? If the block is cut back for a T Vent but one not fitted and the airbrick is there then clear passage for airflow. In a cavity I could understand (with a squint) but here?

 

cheers,

-Dean